Folding apparatus

ABSTRACT

Apparatus for folding sheet material in which apparatus panels disposed in opposed relation form a receiving surface for the receipt of sheet material to be folded. The panels are provided with vacuum ports which the sheet material overlies and the production of suction pressure retains the sheet material securely on the forming board. The panels are pivotally mounted such that they are movable between a position in which the oppositely disposed panels lie in substantially planar relation and a position in which the panels are in substantially parallel relation. Tucking of sheet material transversely to provide fold lines in the material is accomplished by shaping the panels to appropriate configurations. A preferred form of the apparatus includes a plurality of the folding boards supported on a carrier permitting continuous operation. Additionally, mechanism mounted on the carrier provides for assisting tucking or folding operations.

United States Patent Spencer et al.

FOLDING APPARATUS Inventors: Harvey J. Spencer, Green Bay;

Eugene W. Wittkopf, Little Suamico, both of Wis.

Assignee: Kimberly-Clark Corporation,

Neenah, Wis.

Filed: Nov. 15, 1973 Appl. No.: 4 16,050

Related US. Application Data [62] Division of Ser. No. 177,301, Sept. 2, 1971, Pat. No.

[52] US. Cl 270/61 R [51] Int. Cl. BGSH 45/00 [58] Field of Search 270/61 [56] References Cited UNlTED STATES PATENTS 2,328,814 9/1943 Laukhuff 270/61 R Primary ExaminerRobert W. Michell Assistant ExaminerA. Heinz Attorney, Agent, or F irm-Kimberly-Clark Corporation [5 7] ABSTRACT Apparatus for folding sheet material in which apparatus panels disposed in opposed relation form a receiving surface for the receipt of sheet material to be folded. The panels are provided with vacuum ports which the sheet material overlies and the production of suction pressure retains the sheet material securely on the forming board. The panels are pivotally mounted such that they are movable between a position in which the oppositely disposed panels lie in substantially planar relation and a position in which the panels are in substantially parallel relation. Tucking of sheet material transversely to provide fold lines in the material is accomplished by shaping the panels to appropriate configurations. A preferred form of the apparatus includes a plurality of the folding boards supported on a carrier permitting continuous operation. Additionally, mechanism mounted on the carrier provides for assisting tucking or folding operations.

1 Claim, 23 Drawing Figures PATENTEU SEP 1 5 I975 SHEET FIG.

PATENTEU SE? 1 5 75 SHEET 9 FIG. ll

PATENTEU 35? I 5 i YS SHEET FOLDING APPARATUS This application is a division of copending application Ser. No. 177,301 filed Sept. 2, 1971, now U.S. Pat. No. 3,782,714 issued Jan. 1, 1974.

. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to sheet folding apparatus and more particularly concerns apparatus for the folding of disposable absorbent articles such as diapers into contoured configurations so that the article conforms readily to a wearer.

2. The Invention-With Relation to the Prior Art The folding of flexible materials, and specifically materials having a somewhat non-uniform structure, is of increasing importantas disposable materials become more prominent in commerce. The folding is required to be uniform from article to article to accommodate modern packaging techniques and'to insure commercial acceptability. Exemplary of articles demanding accuracy and reproducibility in'folding while yet necessarily being folded on a production basis are disposable diapers, particularly those which are contoured to accommodate themselves to the shape of wearers, such as young children. A diaper of the kind under consideration is disclosed in Hrubecky US. Pat. No. 3,196,874.

Additionally, sheet materials of the paper tissue kind and those which combine tissue with nonwoven materi als in the toweling, bib, napkin and like fields are articles which require folding to desired shapes at a substantial production rate. I

It is, accordingly, a primary object of this invention to provide apparatus for the folding of sheet material which is widely applicable in the paper and similar producing industries. 1

An important object of theinvention is to provide a novel folding board arrangement which has particular utility as a component of apparatus which automatically folds sheet material at a substantial production rate. The board provides for the folding of material lengthwise of itself and may substantially simultaneously provide for the making of transversefolds or folds angularly disposed to the length and width of the sheet material as desired.

A further and more specific object of the invention is to provide apparatus for folding a disposable diaper along a medially located line lengthwise of itself and to tuck edge portions of the diaper inwardly centrally of the diaper length to provie a generally triangular fold in the diaper with a centrally disposed pocket.

Other objects and advantages of the invention will be more readily apparent by reference to the following de tailed description and accompanying drawings wherein:' 7

FIG. 1 is a perspective view of a diaper folding apparatus incorporating a plurality of folding boarus .in accordance with a preferred embodiment.v of the invention;

FIG. 2 is an essentially schematic view in side elevation illustrating fold positions of a diaper folding board as the board progresses in the operation of ,theapparatus of FIG. 1 from the machine inlet to the machine outlet positions; v

FIGS. 3 and 3a are fragmentaryand sectional views which, taken together, illustrate the mechanism for effecting folding board operations, the views being taken in the direction of the position of machine outlet;

FIG. 4 is a somewhat enlarged and fragmentary sectional view taken on line 4-4 of FIG. 3;

FIG. 4a is a view like that of FIG. 4 to a somewhat smaller scale illustrating particularly the camming mechanism for actuation of the folding boards and associated equipment;

FIGS. 5 and 5a through FIGS. 8 and 8a illustrate corresponding positions of the diaper folding mechanism and the fold in the diaper itself at specific stages of the operation; 7

FIGS. 9 and 10 are detail views of the diaper folding mechanism;

' FIG. 11 is a schematic view illustrating a mode of determining relative shaft positions for operation of the specific folding mechanism;

FIG. 12, 13 and 14 are detail views of a pusher mechanism for effecting diaper removal from the folding mechanism; 7

FIGS. 15 and 16 are detail views illustrating an arrangement of assist fingers for effecting diaper folding with a deep centrally positioned diaper pocket; and

FIG. 17 is a view in plan of a power source arrangement for the equipment operation described.

In broad aspect the mechanism in accordance with the invention includes a folding board which moves in a predetermined path and intercepts an article to be folded, such as the mentioned disposable diaper. It is apparent that other sheet material may be folded to predetermined configurations in accordance with the principles of the invention and that the diaper structure in its passage through the mechanism fully illustrates these principles. The diapers in the preferred practice of the invention move to the folding board in essentially planar condition.

The folding board includes a pair of oppositely disposed panels arranged to be pivoted from a position in which the panels form essentially a plane to receive the planar disposed diaper, to a position in which the panels' lie in substantially parallel relation with the diaper folded lengthwise about a medial transverse fold line of the diaper. The panels, for the purpose of securely retaining the diaper as it is folded, each include rearwardly disposed on the panel a housing communicating with vacuum ports. Accordingly, as a diaper is transferred to the folding board, a leading edge of the diaper lies across the leading end of the first panel and the application of vacuum holds it in fixed position relative to the panel. As the folding board moves, the diaper is further drawn onto the second and trailing panel, and the trailing edge of the diaper lies across and is retained by the vacuum condition existing at the ports of the trailing end of the second panel. I

The. panels are suitably shaped to provide for fold lines in the diaper additionally to the medial transverse fold line. In specific application the panels are of a generally triangular configuration and of the same dimensions so that, upon folding the flexible material, the product shape is substantially symmetrical about the medial fold line. The attainment of the additional fold lines is with the aid of tucking elements which suitably function simultaneously with the pivotal movement of the panels and may be actuated from machine components common to the panels or from components independently actuated.

For production operations a plurality of the folding boards are provided on a carrier which traverses a closed path from a diaper inlet zone to a diaper outlet zone, returning to the inlet zone for the reception of a continuing supply of diapers to be folded. The folding board panels are suitably each controlled in their movement from the planar open position to a parallel or closed folded position and return to the open posi,

tion by cam means moving in a fixed track and supported by the carrier. Additionally, a cam actuated device is provided to assist diaper removal from the folded or collapsed folding board.

In the specific embodiment disclosed, the carrier includes an arrangement to assist folding and provide a relatively deep pocket centrally of the diaper. This arrangement acts in conjunction with each forming board as it approaches the diaper outlet zone and is synchronized with the movements of the carrier and folding boards to permit entry to and withdrawal from the partially folded diapers in a reciprocating action.

The diapers in their folded condition, with the folding board panels lying in generally parallel relation to each other, are relatively fixed in position even after removal of the vacuum conditions. To aid removal, each folding board includes means, suitably cam actuated, for urging the diapers from the boards while the panels are in their folded position.

Referring to the drawings more in detail, the numeral 11 in FIGS. 1 and 2 indicates a diaper moving in planar arrangement in the direction of the arrows toward a transfer roll 13 which carries a fixed vacuum box 15. The diaper 11 may be of any construction suitable to be folded in the manner such as is, for example, generally indicated in FIG. 8a. The diapers commonly are formed of a composite of flexible materials including a liquid impermeable ply as of polyethylene, an absorbent ply as of wood pulp fibers, and a soft bodycontacting ply of reinforced tissue as is well-known in the art. Further details of construction are not essential to the practice of this invention but a useful diaper construction is more specifically shown in US. Pat. No. 3,196,874 previously mentioned herein.

A plurality of the diapers as particularly indicated in FIG. 2 move in succession in spaced apart relation to the roll 13 and are carried to the roll on a wire screen 17 under the influence of vacuum applied from a fixed vacuum box 19. The screen 17 is conveniently supported on rollers in well-known manner, one roll being indicated at 21 in FIG. 2.

The folding apparatus is generally designated by the numeral 22 (FIGS. 1 and 2). It includes a pair of oppositely disposed carrying plates 23, 24 retained in spaced relation by a plurality of horizontally extending spacers 12 which are also hollow and serve as conduits for air flow in a vacuum system later to be described. The plates 23, 24 are-fixedly retained on a main shaft 25 (FIGS. 1, 2 and 3) for rotation therewith by conventional keys as at 28. Framing 26, which includes a transverse member and a pair of uprights, support the shaft 25 rotatably on bearings as indicated at 26a (FIG. 3). As shown most clearly in FIGS. 1 and 2, a plurality of folding boards generally indicated at 27 are provided and carried in rotation between the plates 23, 24 for the purpose of acting on a corresponding plurality of diapers simultaneously to fold them from the flat position of FIG. 1 to the position generally indicated in FIG. 8a. The sequence of folding steps is illustrated in FIGS. 5a through 8a, and the-corresponding folding board positions are shown in FIGS. 5 through 8.

Referring now to the movement of the folding boards 27, in the present instance the general: type of mechanism is a cam actuated one. For this purpose the frame 26 fixedly carries a pair of cam plates 29, one on each side of the apparatus (FIGS. 3 and 3a). Two plates 29 are employed in practice for smooth operation. For convenience one cam plateand its associated equipment for rotation of the panels of a folding board, as illustrated particularly in FIG. 3, will be described in detail but it is to be understood that the operations on each side of the machine for actuation of the panel folding mechanism will be similar. Each of the folding boards 27 is actuated in thesame way by separate cam means, as may be clearly seen from FIGS. 4 and 4a. Corresponding parts, where convenient, are designated by corresponding numerals. Also in FIGS. 3 and 3a for sake of clarity in illustration, the panels are at to their normal position.

The panels 27a, 27b of a folding board are actuated through a single cam on each cam plate 29. Thus, cam plate 29 receives a cam follower 30 which moves in a cam track 31. The follower 30 is carried by a bell crank 32 which has a hub 33 of rotation and carries at one end gear teeth 34 arranged as a sector of a gear. The teeth 34 mesh with a toothed gear 35 fixedly retained (FIG. 3) on an inner hollow tubular shaft 36 (FIG. 5). The shaft 36 is integral with bevelled gear 37 which meshes with pinion 38, the latter meshing with bevelled gear 39 for rotation with. respect to shaft 36. Gear 39 is integral with outer shaft 41. Bearings indicated at 40 support the gear 39 and outer shaft 41 for rotation with respect to the inner shaft 36, the concentric shafts 36 and 41 having opposite rotational directions. Panel support arms designated at 42a and 42b are respectively secured to outer shafts 41 and 36.

The panels 27a, 2712 at their oppositely disposed rearward ends, as shown in FIG. 5, have housings 45 and vacuum ports 44 which communicate the housing interiors with the atmosphere. Conduits 43 (FIGS. 3 and 3a) connect to vacuum pump means (not shown) and air flow may take place from the housing interiors through the second and hollow tubular arms 42b and hollow shafts 36. Each housing is closed off interiorly at one end as most clearly shown in FIG. 3 to provide for air passage from the folding board surface to the housing interior and vacuum application to material resting over the ports 44. A second support arm 42b, and a first support 42a (which is suitably solid and blocked off from the interior of housing 45 to provide for the vacuum effect) are connected with each panel for driving it in rotation as illustrated in FIGS. 5 through 8. For this purpose the radial distance of the arms 42a, 42b are equal from the axial center of the hollow shaft 36 so that each arm cooperates smoothly in providing for the movement.

The numeral 46 (FIGS. 1 and 3) generally designates a bracket for retention of the gear cluster 37, 39 to which reference has already been made. Each bracket includes amounting plate 47 secured fixedly to a circular carrying plate for traveling in rotation with the plate. As indicated in FIG. 3, shaft 41 is rotatably mounted with respect to and supported by this plate 47. This permits free rotation of the outer shaft 41 relative to the plate 47. The other outer oppositely disposed plate 48 of each bracket 46 is hollow, providing for air flow to the conduits 43 from the arms as already noted (FIGS. 3 and 3a).

The movement of the arms to effect panel movements is permitted by the gimbal joint arrangement, more specifically described in connection with FIGS. 9 and 10. As shown, each arm 42a and 42b fixedly carries a mount 49. The mount 49 threadedly receives a bear ing screw 50 (FIG. which is itself pivotally retained on block 51 by roller bearing 54. The pivot block 51 also includes a second bearing screw 52 which is theadedly received in a mount 53 carried on the extremity of a wing or fold member 56. Provision for rotation of the bearing screw 52 is made by the roller bearing 55 similar to bearing 54. Member 56, as indicated at 57, is hingedly connected to a second and similar wing 58. The wings 56, 58 in their movement, as indicated in FIGS. 5 through 8, effect folding of the diaper as indicated in the views shown in FIGS. 5a through 8a. More specifically, shafts 36 and 41, driven as already indicated and which are associated with the arms 42a, 42b, cause the arms 42a, 42b to move through the positions indicated in FIGS. 5 to 8. As such movement takes place, the wings 56, 58 are caused to collapse on them selves and also inwardly against the diaper, urging the diaper into a fold condition such as is indicated, for example, at 11h and 11g in FIG. 6a.

The wings 56, 58 themselves collapse inwardly upon movement of the arms 42 due to the gimbal joint arrangement illustrated in FIGS. 9 and 10 and previously described. The lines of fold are determined by selection of the relative axial alignment of the axes of bearing screws 50, 52 as indicated at 50' and 52 in the schematic illustration FIG. 11. (In FIG. 11, for convenience, the schematically illustrated gimbal joint components have the same numerals in other figures but are primed.) More specifically, the line GA, for example, extending from the simulated diaper center to a diaper corner and beyond provides one axis while a line HA projected from the point I-I provides a second axis 52'. These axes lie along the intended lines of fold of the diaper and augularly to the medial transverse fold line EF. When oriented, as shown in FIG. 11, the diaper, upon movement of the wings 56, 58 as indicated, results in primary diaper sections 11a, 11b and outer side folds 11c, 11d, 11g, and 11h as well as inwardly disposed folds lle, 11f, lli, and 11j.

It will, accordingly, be understood from the foregoing that in the rotation of plates 23, 24 the brackets 46 and their associated plates 47 rotatably secured to the hubs 33 move the followers 30 in their respective tracks 31 and through the mechanism previously described, caus ing the panels 27a, 27b of the folding boards to move through the steps indicated in FIGS. 5 through 8. Specifically, the panels which are spaced apart lengthwise in end-to-end relation to define a gap for forming a transverse fold line in the diaper are oscillated or rotated to a back-to-back position with the gap maintained. In the course of this action a diaper which has been delivered in lengthwise planar disposition to a folding board as in FIG. 2 is completely folded in the course of its passage from the transfer roll 13 to the removal jaws 14. Also, in the course of this action, the diaper is subjected to vacuum conditions as indicated in FIG. 2. Thus, at the first station 1p vacuum is applied to the forward end of panel 27a by drawing air through the vacuum ports 44 which are positioned forwardly on the folding board 27. The air flow is to the shaft 36,

conduit 43 (FIG. 3) and through spacer-conduit 12 to the rotary valve 9 and port 10 of the valve, the exhaust to vacuum being by legend indicated in FIG. 2. The rotary valve 9 is of a conventional type in which openings 8 in circular plate 23 (FIG. 2) and also plate 24 are covered and uncovered sequentially in known manner in plate rotation relative to the valve to provide respectively for stopping and starting of air flow.

In the drawing the solid lines indicate air flow from the vacuum ports to the hollow shafting. The solid lines indicate air flow or the presence of vacuum conditions at the leading end of the folding board; the dash lines indicate the presence of vacuum conditions at the rearward end of the board, and the absence of solid or dash lines indicates that vacuum conditions are not present.

Accordingly, as shown at positions 2p through 4p (FIGS. 2 and 4a), the diaper is retained in positions as the panels in their movements cause folding of the diaper longitudinally about the median transverse fold line. As the folding board traverses its path from position 4p to 5p, the vacuum condition is removed and the diaper is free to move from the ports and to be withdrawn by suitable mechanism at station 5p. In the travel to the position 6p under the influence of the cam means 30, the folding board opens toward a substantially planar condition.

To assist the removal of the diaper at the station 5p (FIG. 2) the mechanism as is particularly illustrated in FIG. 3 and more in detail in FIGS. 12 to 14 is provided in association with each folding board. As illustrated in FIGS. 3 and 4, the frame 26 carries a cam plate 60 for receiving a plurality of cam followers 61 in the track 62. Each follower 61 is retained by a bell crank 63 (FIG. 4). Each bell crank is provided with a hub 64 which is received on a shaft 65. Each shaft 65 through bearing 66 rotatably supports the bell crank from the rotatable carrier plate 24. A bearing retainer nut 67 provides for retention of a shaft 65 on a bell crank 63. Each bell crank 63 carries teeth 68 which mesh with the teeth of a gear 69 supported by a bushing 70 which itself receives a key 71 (FIG. 3). A key 71 is received by each shaft 72 so that a gear 69 drives a shaft 72. Each shaft 72 is'suitably supported by bearings 73 as indicated particularly in FIG. 3. As is apparent in the rotation of the carrier plate 24, the shafts 72 are driven through the followers 61 of bell crank 63.

A circular plate 74 (FIG. 4) suitably termed a pusher support plate is secured for rotation with shaft 25 through key 75 (FIG. 3). The pusher support plate 74 rotatably supports each shaft 72 of the diaper pusher assembly. Each shaft 72 carries a sector gear 76 which is retained on the shaft by a clamp screw 76a. Each sector gear 76 meshes with and drives a rack 77. A fixedly positioned backing roller 78 (FIG. 4) associated with each pusher assembly guides each rack in its rectilinear movement as does a guide block 79. Each rack 77 on its extremity is provided with a suitably shaped pusher 80 (FIGS. 4, and 12-14).

Referring now to FIGS. 12-l4 inclusive, a pusher 80 of each folding board acts against brackets 81 which form part of the mechanism for assisting diaper removal from the diaper folding boards. Only one pusher assembly will now be described in detail. Pins 82 carried on opposite ends of a spring 83 are retained by the forward bracket 81 and rearward bracket 84. Further, bracket 81 is fixedly retained on a movable slide 85 on the under side of each of the panels 27a, 27b of the folding board. Each slide carries a block 86 of nylon, the slide and block being retained together by nut and bolt assemblies 87.

The nylon block 86 moves in a slot 88 extending in each of the panels of the folding boards as indicated most clearly at 27b in FIG. 12. Accordingly, when a pusher 80 is actuated by the movement of the shaft 72 under control of a cam follower 61, a diaper on the folding board will be urged outwardly of the board and the board and the board assumes the position of FIG. 13. As most clearly seen from FIG. 3, the actuation of the diaper removal device is governed by the relationship of a cam follower 61 to that of the cam follower 30, and these are so synchronized that the diaper is urged from the plate at the proper station as indicated in FIG. 4a.

It has been found desirable to assist the action of the wings or folding members 56, 58 in the folding of the diapers and to achieve a relatively deep central pocket. For this purpose there is provided the mechanism illustrated in FIGS. 15 and 16. Referring first to FIG. 15, there is indicated at 90 a pair of fold assist tubular rods 90 through which an air flow may be directed. These rods are received on pivot blocks 91 which include a base 92 and, since each rod arrangement is similar, only one will be described in detail. The base 92 receives therethrough a screw 93 (FIG. 16). A cross-ann 94 receives the screw 93 in threaded engagement and nut 95 abuts the cross-arm retaining the screw and cross-arm in fixed relation. One extremity of the screw 93 (FIG. 16) rotatably receives block 91; for this purpose the bearing 96 is provided to effect the rotational support. Each of rods 90 is thus pivotally mounted with respect to cross-arm 94.

The cross-arm 94 is slotted at 97 and receives cap screws 98 which are threadedly secured in an extremity of bar 99. The bar 99 is provided with stud shafts 100 (FIG. 17) which rotate within the bar, the stud shafts being carried on extremities of the cranks 101. A first crank 101 receives shaft 102 while the second crank 101 receives shaft 103 (FIGS. 15 and 17). The bar 99 describes an essentially orbital or generally circular motion with the centers of shafts 100 moving in an arcuate fashion about the centers of shafts 102, 103.

Shafts 102 and 103 are driven in a manner more clearly seen from FIG. 17. In FIG. 17 the numeral 105 designates an electric motor source of power. Motor shaft 106 carries pulley 107 which, through belt 108, drives pulley 109 and shaft 110. A suitable right angle drive arrangement 112 connected by couplings 111 from shaft to shaft 113 provides for actuation of gear 114. Gear 114 drives main gear 115 carried on main shaft 25 to which reference has already been made. Second gear 116 on shaft 113 drives gear 117 and hence shaft 118 and gear 119. The latter gear cooperates with gear 120 to drive shaft 102. Shaft 102 carries pulley 121 which drives timing belt 122 and pulley 123 on the shaft 103. Thus, shafts 102 and 103 are rotatably supported by frame 26 and are arranged to rotate in timed relation. The rotation of shafts 102, 103 cause movement of the cranks 101 and hence movement of the arm 99 and cross-arm 94.

Crossarm 99 provides for the movement of the fold assist rods 90 in an arcuate motion so that the rods 90 may enter the diaper in an arcuate motion as the diaper is being folded and as the diaper and the folding board carrying it itself move in a closed path.

For the purpose of guiding the inward and outward movement of the rods 90 freely of other parts of the mechanism and the diaper itself, a linkage system controls motion of the rods 90 in a generally oscillating manner. More specifically, from each fixed frame support 26 a bracket 130 is provided. A pair of ball joints 124 carrying a rigid link 125 (FIG. 16) are respectively secured to brackets and to the base 92 of the block 91 for free pivotal movement. Retaining means 127 of conventional nature such as a threaded bolt and screw effect securing to the brackets 130 and with rigid arms 125 tend to limit the movements of each of the bases 92 carrying the rods 90.

The retaining means 128 serve to retain rigid arms 125 to base 92 and base 92 is slotted to provide for adjustability and to permit accurate location of the retaining means.

The rods 90 are hollow for the purpose of directing air through them against the diaper to assist folding and also to aid release from the diaper. For this purpose air lines 126 communicate with the rods as indicated in FIG. 15.

The diapers passing from the folding boards to the jaws 14 are ready for packaging and may be directed to suitable cartons in known manner.

Mechanism as described is capable of handling diapers of a size of about 12 /2 inches by 17%. inches at a rate of up to 200 diapers per minute, and more. The folding boards, panels having their edges which taper from the relatively wide rearward end to a narrow forward terminating at the gap between panels, are as described suitably on 24 inch centers about the carrier periphery, and the carrier plates 23, 24 rotate at a speed of about 40 rpm.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as defined in the appended claims.

We claim:

1. In apparatus for folding lengths of flexible sheet material having end portions and lateral edge portions, means for feeding a succession of the lengths of sheet material endwise in open substantially planar condition in spaced relation along a path, a frame, a rotatable carrier on the frame having an axis of rotation and comprised of a pair of plates spaced apart along the said axis of rotation, a plurality of folding boards in circumferentially spaced apart relation supported between the plates of the carrier and each comprising a pair of panels forming a surface for the receipt of a length of sheet material to be folded, the panels of a folding board being spaced apart longitudinally of the board to define a gap in the folding board for providing a transverse fold in sheet material on said folding board, support means including rotatable shaft means supporting each of the panels of each folding board for rotation between a position in which the panels are in end-toend substantially planar relation to a position in which the panels are in back-to-back substantially parallel relation, means for rotating said Shaft means, tucking means for infolding the edge portions of sheet material at the gap between said panels, finger means to assist folding of the sheet material and means for actuating the finger means in timed sequence with the rotation of the panels to the back-toback position to provide for entry of the finger means between the panels tal path so that the finger means move inwardly and outwardly between the panels in the rotated back-toback condition of the panels. 

1. In apparatus for folding lengths of flexible sheet material having end portions and lateral edge portions, means for feeding a succession of the lengths of sheet material endwise in open substantially planar condition in spaced relation along a path, a frame, a rotatable carrier on the frame having an axis of rotation and comprised of a pair of plates spaced apart along the said axis of rotation, a plurality of folding boards in circumferentially spaced apart relation supported between the plates of the carrier and each comprising a pair of panels forming a surface for the receipt of a length of sheet material to be folded, the panels of a folding board being spaced apart longitudinally of the board to define a gap in the folding board for providing a transverse fold in sheet material on said folding board, support means including rotatable shaft means supporting each of the panels of each folding board for rotation between a position in which the panels are in end-to-end substantially planar relation to a position in which the panels are in back-toback substantially parallel relation, means for rotating said shaft means, tucking means for infolding the edge portions of sheet material at the gap between said panels, finger means to assist folding of the sheet material and means for actuating the finger means in timed sequence with the rotation of the panels to the back-to-back position to provide for entry of the finger means between the panels to urge said sheet material to the folded condition, said frame having guide means projecting therefrom and the guide means being connected with said finger means for guiding movement of the finger means, and means supporting said finger means for movement in an orbital path so that the finger means move inwardly and outwardly between the panels in the rotated back-to-back condition of the panels. 